Container containing a cobalt carbonyl complex and cobalt carbonyl complex composition

ABSTRACT

A container containing a cobalt carbonyl complex and a gas that contains carbon monoxide, and a cobalt carbonyl complex composition comprising a cobalt carbonyl complex and a solvent, wherein the concentration of carbon monoxide dissolved in the solvent is 0.001 to 1 wt %. 
     Since the cobalt carbonyl complex contained in the above container or the above composition can retain its sublimation properties for a long time without being converted into a stable complex, when a cobalt film is formed by chemical vapor deposition using the container and the composition, a high-quality film can be formed by a simple process, and the production cost of the cobalt film can be reduced due to high use efficiency of the precursor.

TECHNICAL FIELD

The present invention relates to a container containing a cobaltcarbonyl complex and to a cobalt carbonyl complex composition. Morespecifically, it relates to a container containing a cobalt carbonylcomplex, which can store a cobalt carbonyl complex stably and can beadvantageously used to form a cobalt film and to a cobalt carbonylcomplex composition.

BACKGROUND ART

In electronic devices such as DRAM (Dynamic Random Access Memory), thestructures of wires and electrodes are becoming finer and more complexto achieve higher performance, and the improvement of accuracy is nowdesired for the shapes of these devices.

To form electrodes and wires in electronic devices, in general, trenchesare formed at positions where wires or electrodes are to be formed on asubstrate, a metal material which will become wires or electrodes isburied in the trenches, and excess is removed by chemical mechanicalpolishing or the like.

Copper which has high conductivity has been widely used as an electrodematerial or a wire material which is buried in the trenches. To burycopper in the trenches, a plating method is advantageous because it hasan advantage that copper can be buried even in trenches having a highaspect ratio at a high filling rate (refer to JP-A 2000-80494 and JP-A2003-318258).

When a substrate having the trenches is an insulator having noconductivity (such as a substrate made of silicon oxide), a conductivelayer (seed layer) which is a primary coat for plating must be formed onthe surface of the substrate prior to plating. It is known that whencopper comes in contact with an insulator typified by silicon oxide, aphenomenon (generally called “migration”) that a copper atom moves tothe insulator from the copper layer occurs. When the migration of thecopper atom occurs at the interface between copper and the insulator inan electronic device, the electric properties of the device areimpaired. Therefore, a barrier layer must be formed between theinsulator and copper of the electronic device.

In recent years, there has been proposed a technology for attaining theabove object by using cobalt as a material which serves as a seed layerfor burying copper into trenches by plating and also as a barrier layerat the interface between the insulator and copper and by using a specialchemical vapor deposition method (refer to JP-A 2006-328526). In thetechnology disclosed by the above publication, a first substrate onwhich a cobalt film is to be formed and a second substrate having acobalt precursor thereon are arranged close to each other and opposed toeach other, and a cobalt precursor sublimating from the second substrateis supplied onto the first substrate and converted into cobalt on thefirst substrate so as to form a cobalt film. The above publicationdiscloses octacarbonyl dicobalt as the cobalt precursor. With thistechnology, a cobalt film which is uniform in thickness even in theinside of each trench and has high adhesion can be easily formed evenwhen a substrate having trenches with a high aspect ratio is used.Therefore, the above object is attained.

However, it is known that an ordinary cobalt precursor such asoctacarbonyl dicobalt has a storage stability problem that it isgradually converted into a stable complex having low sublimationproperties during storage. When this cobalt complex including a stablecomplex is used as the precursor in the chemical vapor depositionmethod, the stable complex does not sublimate and remains. Therefore, itis necessary to prepare the precursor used for the chemical vapordeposition method in an amount which is much larger than its theoreticalvalue calculated from the weight of the cobalt film to be formed. Sincethe above residue cannot be reused as the cobalt precursor in thechemical vapor deposition method, the formation of the cobalt film bythe chemical vapor deposition method becomes excessively costly.

DISCLOSURE OF THE INVENTION

It is an object of the present invention which has been made in view ofthe above situation to provide means by which a cobalt carbonyl complexcan be stored stably and is advantageously used for the formation of acobalt film by a chemical vapor deposition method after storage.

The inventors of the present invention conducted studies to attain theabove object and found that a cobalt carbonyl complex has excellentstability when it is stored in the presence of carbon monoxide. Theyalso found that especially when the cobalt carbonyl complex is stored ina gas containing carbon monoxide or a solution containing carbonmonoxide, it can be stored extremely stably and even when it is storedfor a long time, the cobalt carbonyl complex does not lose itssublimation properties after storage and can be advantageously used inthe chemical vapor deposition method. The present invention wasaccomplished based on these findings.

That is, according to the present invention, firstly, the above objectsand advantages of the present invention are attained by a containercontaining a cobalt carbonyl complex and a gas, wherein the gas containscarbon monoxide.

Secondly, the above objects and advantages of the present invention areattained by a cobalt carbonyl complex composition comprising a cobaltcarbonyl complex and a solvent, wherein the concentration of carbonmonoxide dissolved in the solvent is 0.001 to 1 wt %.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a container containing a cobaltcarbonyl complex according to an embodiment of the present invention.

EXPLANATION OF REFERENCE SYMBOLS

-   1: container containing a cobalt carbonyl complex-   10: container body-   11: gas introduction port-   12: gas exhaust port-   13: partition-   P: cobalt carbonyl complex-   G: gas containing carbon monoxide

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail hereinunder. “ppm” inthe following description is based on volume when it is used for a gasand based on weight when it is used for a liquid (solution or solvent).

<Cobalt Carbonyl Complex>

The cobalt carbonyl complex in the present invention is a cobalt complexhaving carbon monoxide as a ligand, such as a complex represented by anyone of the following formulas (1) to (4).

Co₂(CO)₈  (1)

Co₃(CO)₉CZ  (2)

(Z is a hydrogen atom, halogen atom, methyl group, methoxy group ortrifluoromethyl group.)

Co₃(CO)₁₂  (3)

Co₄(CO)₁₂  (4)

The cobalt carbonyl complex represented by the above formula (2) is, forexample, a complex represented by the following formula (i)

The cobalt carbonyl complex in the present invention is preferably acomplex represented by the above formula (1) or (4), particularlypreferably octacarbonyl dicobalt.

It is known that when the cobalt carbonyl complex is stored by a methodcommonly used by people having ordinary skill in the art, it isgradually converted into a stable complex and its sublimation propertiesare lost. However, when it is stored in the presence of carbon monoxide,it can be stored stably. Particularly when it is stored in a gascontaining carbon monoxide or a solution containing carbon monoxide, itcan be stored very stably. This knowledge discovered by the inventors ofthe present invention has produced the following two embodiments.

A first embodiment of the present invention is a container containing acobalt carbonyl complex and a gas, wherein the gas contains carbonmonoxide.

A second embodiment of the present invention is a cobalt complexcomposition comprising a cobalt carbonyl complex and a solvent, whereinthe concentration of carbon monoxide dissolved in the solvent is 0.001to 1 wt %.

The two embodiments of the present invention will be describedhereinunder.

<Container Containing a Cobalt Carbonyl Complex>

The container containing a cobalt carbonyl complex according to thefirst embodiment of the present invention is a container containing acobalt carbonyl complex and a gas, wherein the gas contains carbonmonoxide as described above.

[Gas]

The gas stored in the container containing a cobalt carbonyl complex ofthe present invention may be a gas composed of carbon monoxide alone ora mixed gas of carbon monoxide and another gas. The other gas which maybe used herein is preferably an inert gas such as nitrogen, argon orhelium.

The concentration of carbon monoxide contained in the gas contained inthe container containing a cobalt carbonyl complex of the presentinvention is preferably 10 to 100 vol %, more preferably 30 to 100 vol%, much more preferably 50 to 100 vol %. Further, the gas contained inthe container preferably contains substantially no oxygen. Morespecifically, the concentration of oxygen contained in the gas ispreferably not more than 500 ppm, more preferably not more than 100 ppm,much more preferably not more than 50 ppm, particularly preferably notmore than 10 ppm. When the above gas is contained in the containertogether with the cobalt carbonyl complex, the storage stability of thecobalt carbonyl complex is significantly enhanced and even when thecobalt carbonyl complex is stored for a long time, the cobalt carbonylcomplex is hardly converted into a stable complex having low sublimationproperties.

The inside pressure of the container containing a cobalt carbonylcomplex is not particularly limited but preferably 5×10² to 1×10⁷ N/m²,more preferably 1×10³ to 1×10⁶ N/m², much more preferably 5×10³ to 1×10⁵N/m², particularly preferably 1×10⁴ to 1.2×10⁵ N/m².

The partial pressure of carbon monoxide in the container containing acobalt complex is not particularly limited but preferably 5×10¹ to 1×10⁷N/m², more preferably 5×10² to ×1×10⁶ N/m², much more preferably 1×10³to 5×10⁵ N/m², particularly preferably 5×10³ to 1.2×10⁵ N/m², mostpreferably 1×10⁴ to 1.1×10⁵ N/m².

To contain the gas containing carbon monoxide in the container, forexample, a method in which the cobalt carbonyl complex is contained inthe container in the gas containing carbon monoxide, or a method inwhich the cobalt carbonyl complex is contained in the container filledwith the gas containing carbon monoxide may be employed.

[Container]

A container which can contain the above-described cobalt carbonylcomplex and the above-described gas, can store them hermetically andpreferably has a structure and a material that enable the cobaltcarbonyl complex to sublimate therefrom can be advantageously used asthe container containing a cobalt carbonyl complex of the presentinvention.

Preferably, the above container has a container body and a lid which canclose up the container when it is mated with the container body, or hasa container body and a gas introduction port and a gas exhaust portformed in the container body. In the case of the latter, the above gasintroduction port and the gas exhaust port are closed up with a lidduring storage.

The outer shape of the container body may be cylindrical or polygonalcolumnar. The volume of the container body is preferably 1×10¹ to 1×10⁶cm³, more preferably 5×10² to 5×10⁵ cm³. The material of the containerbody is not particularly limited if it has low reactivity with thecobalt carbonyl complex and can withstand heat at the time ofsublimation, and examples thereof include stainless steel, aluminum,polysilicon, titanium, other metals and alloys comprising two or more ofthem; plastics such as polytetrafluoroethylene and polyethylene; andceramic materials or glasses such as quartz, borosilicate glass, pureglass, boron nitride and silicon carbide. Out of these, metals such asstainless steel and alloys are preferred.

At least partitions or a filler may be provided in the container. Whenat least partitions or a filler is provided in the container, the heattransmission area can be made large during the sublimation of the cobaltcarbonyl complex from the container, thereby making it possible to heatthe complex uniformly and carry out stable and efficient sublimationadvantageously. When the cobalt carbonyl complex is locally heated,conversion into a stable complex readily occurs from that portion. Whenat least partitions or a filler is provided in the container, this canbe avoided.

The above partitions are for dividing the inside of the container into aplurality of chambers and preferably do not reach the top of thecontainer. The volume of each chamber divided by the partitions is, forexample, 1×10° to 1×10⁵ cm³. The partitions may have a portion (forexample, a hole) communicating with adjacent chambers. The material ofthe partitions may be the same as those enumerated for the material ofthe container body, and is preferably the same as the material of thecontainer body.

The above filler is a material which fills the inside of the containerwith a certain void ratio and preferably fills 1 to 90 vol % of a lowerportion of the container with a void ratio of preferably 10 to 80 vol %.The material of the filler is, for example, stainless steel, glass,ceramic or fluororesin, preferably stainless steel. The shape of thefiller is, for example, spherical, polygonal columnar, cylindrical,coil-like, spring-like or fibrous. Examples of the filler includepackings for distillation such as DIXON Packing, HELI PACK and Fenske.The size of each unit material constituting the filler is, for example,0.1 to 10 mm.

The filling rate of the cobalt carbonyl complex in the containercontaining a cobalt carbonyl complex of the present invention ispreferably 1 to 80 vol %, more preferably 20 to 60 vol % of the volumeof the container body.

The container containing a cobalt carbonyl complex according to apreferred embodiment of the present invention will be described in moredetail hereinunder with reference to the accompanying drawing.

FIG. 1 is a schematic sectional view of the container containing acobalt carbonyl complex according to the embodiment of the presentinvention.

The container 1 containing a cobalt carbonyl complex shown in FIG. 1 hasa container body 10 and a gas introduction port 11 and a gas exhaustport 12 formed in the container body 10. The gas introduction port 11and the gas exhaust port 12 are closed up with a sealable lid (notshown) during storage. The container 1 further has a plurality ofpartitions 13 for dividing the container body into a plurality ofchambers. The partitions 13 do not reach the top of the container body,and a fluid can move from the gas introduction port 11 to the gasexhaust port 12 through the chambers. A cobalt carbonyl complex P iscontained in each chamber, and a gas G containing carbon monoxide iscontained in remaining spaces in the container body and the chambers.

When the cobalt carbonyl complex is to be stored in the above-describedcontainer containing a cobalt carbonyl complex, it is stored in a gascontaining carbon monoxide which increases the stability of the cobaltcarbonyl complex significantly. Therefore, the cobalt carbonyl complexcan be stored stably for a long time without being converted into astable complex having low sublimation properties. The temperature forstoring the cobalt carbonyl complex is preferably −30 to 80° C., morepreferably 10 to 50° C., particularly preferably 35 to 50° C. Since thecontainer containing a cobalt carbonyl complex of the present inventioncan be used for sublimation as it is so as to form a cobalt film, it hasan advantage that the formation of a cobalt film can be carried outefficiently by a very simple process.

[Method of Forming a Cobalt Film]

A description is subsequently given of a method of forming a cobalt filmby chemical vapor deposition using the above container containing acobalt carbonyl complex.

The method of forming a cobalt film is characterized in that the abovecontainer containing a cobalt carbonyl complex is heated to sublimatethe cobalt carbonyl complex from the container so as to supply asublimate onto a substrate and convert the cobalt carbonyl complex intocobalt on the substrate. Thereby, the cobalt carbonyl complex can besublimated at a high efficiency and converted into cobalt.

Heating for sublimating the cobalt carbonyl complex from the containercontaining a cobalt carbonyl complex is carried out to ensure that thetemperature of the cobalt carbonyl complex contained in the containerbecomes preferably 25 to 150° C., more preferably 30 to 100° C., muchmore preferably 35 to 50° C. The inside pressure of the container forsublimating the cobalt carbonyl complex is preferably 1×10¹ to 1×10⁶N/m², more preferably 1×10² to 5×10⁶ N/m², much more preferably 5×10¹ to1.2×10⁵ N/m².

To supply the sublimate of the above cobalt carbonyl complex onto thesubstrate, the generated sublimate is carried to a position near thesubstrate by a suitable carrier gas or a pressure difference. To carrythe sublimate to a position near the substrate by a carrier gas, it isconvenient that a container having a container body and a gasintroduction port and a gas exhaust port formed in the container bodyshould be used and installed in such a manner that the gas exhaust portis located near the substrate and the container should be heated whilethe carrier gas is introduced from the gas introduction port. Examplesof the carrier gas used herein include inert gases such as nitrogen,argon and helium, and reducing gases such as hydrogen and carbonmonoxide. To supply the sublimate to a position near the substrate by apressure difference, it is convenient that a container having acontainer body and a gas introduction port and a gas exhaust port formedin the container body should be used, a substrate should be placed in areactor different from the container, the gas exhaust port of thecontainer should be connected to the reactor, and a vacuum pump shouldbe used to reduce the inside pressure of the reactor.

The cobalt carbonyl complex supplied onto the substrate is convertedinto cobalt on the substrate, thereby forming a cobalt film on thesubstrate. The conversion of the cobalt carbonyl complex into cobalt onthe substrate may be carried out by heating the surface of thesubstrate. The temperature of the surface of the substrate forconverting the cobalt carbonyl complex into cobalt is preferably 50 to300° C., more preferably 70 to 250° C., much more preferably 100 to 200°C.

The material of the substrate on which a cobalt film is to be formed bythe method of forming a cobalt film by using the container containing acobalt carbonyl complex and the feature of the cobalt film to be formedwill be described hereinafter.

<Cobalt Carbonyl Complex Composition>

The cobalt carbonyl complex composition according to the secondembodiment of the present invention is a composition comprising a cobaltcarbonyl complex and a solvent, wherein concentration of carbon monoxidedissolved in the solvent is 0.001 to 1 wt %.

The concentration of the cobalt carbonyl complex in the cobalt carbonylcomplex composition of the present invention is preferably 0.1 to 50 wt%, more preferably 1 to 30 wt %.

[Solvent]

Examples of the solvent contained in the cobalt carbonyl complexcomposition of the present invention include aliphatic hydrocarbons,alicyclic hydrocarbons, aromatic hydrocarbons, alcohols, ethers, ketonesand halogenated hydrocarbons. At least one of them is preferably used.

The above aliphatic hydrocarbons include n-hexane, n-heptane, n-octane,n-nonane and n-decane; the above alicyclic hydrocarbons includecyclohexane, cycloheptane and cyclooctane; the above aromatichydrocarbons include benzene, toluene and xylene; the above alcoholsinclude methanol, ethanol, propanol, isopropanol and butanol; the aboveethers include diethyl ether, dipropyl ether, dibutyl ether, ethyleneglycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycolmethyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycoldiethyl ether, diethylene glycol methyl ethyl ether, tetrahydrofuran,tetrahydropyran and p-oxane; the above ketones include acetone, methylethyl ketone, cyclohexanone and diethyl ketone; and the abovehalogenated hydrocarbons include methylene chloride, tetrachloroethane,chloromethane and chlorobenzene.

At least one solvent selected from the group consisting of n-pentane,n-hexane, n-heptane, cyclopentane, xylene and toluene out of these ispreferably used, and at least one solvent selected from the groupconsisting of n-hexane and toluene is particularly preferably used.

The concentration of carbon monoxide dissolved in the solvent ispreferably 0.005 to 0.5 wt %, more preferably 0.05 to 0.3 wt %. Theconcentration of carbon monoxide dissolved in the solvent is preferably0.001 to 100 moles, more preferably 0.01 to 10 moles, much morepreferably 0.05 to 5 moles, particularly preferably 0.1 to 1 mole basedon 1 mole of the cobalt carbonyl complex. When the concentration ofcarbon monoxide dissolved in the solvent falls within the above range,the stability of the cobalt carbonyl complex in the solution becomesvery high, whereby when the cobalt carbonyl complex composition isstored for a long time, conversion into a stable complex hardly occurs.The temperature for storing the cobalt carbonyl complex composition ispreferably −30 to 80° C., more preferably 10 to 50° C., particularlypreferably 35 to 50° C. When a cobalt film is formed from this cobaltcarbonyl complex composition by chemical vapor deposition, the useefficiency of the cobalt carbonyl complex becomes high.

The concentration of oxygen dissolved in the solvent is preferably notmore than 500 ppm, more preferably not more than 100 ppm, much morepreferably not more than 50 ppm, particularly preferably not more than10 ppm.

[Other Components]

The cobalt carbonyl complex composition of the present inventioncomprises a cobalt carbonyl complex and a solvent and has aconcentration of carbon monoxide dissolved in the solvent of 0.001 to 1wt %. As long as the effect of the present invention is not impaired, itmay optionally comprise other components. The other components include asurfactant, a silane coupling agent and a polymer.

[Method of Producing a Cobalt Carbonyl Complex Composition]

The cobalt carbonyl complex composition of the present invention can beproduced, for example, by a method comprising the steps of:

bubbling a gas containing carbon monoxide into a solvent; and

dissolving a cobalt carbonyl complex in the solvent obtained by theabove step,

or a method comprising the steps of:

dissolving a cobalt carbonyl complex in a solvent to produce a cobaltcarbonyl complex solution; and

bubbling a gas containing carbon monoxide into the obtained cobaltcarbonyl complex solution.

When the cobalt carbonyl complex composition of the present inventioncomprises the above other components, the other components may be addedat any time in any one of the above steps.

The temperature of the solvent in the step of bubbling a gas containingcarbon monoxide into the solvent or the cobalt carbonyl complex solutionis preferably −80 to 100° C., more preferably −30 to 50° C., much morepreferably −10 to 30° C.

The gas containing carbon monoxide is a gas composed of carbon monoxidealone or a mixed gas of carbon monoxide and another gas. Preferredexamples of the other gas used in the latter include inert gases such asnitrogen, argon and helium. When a mixed gas of carbon monoxide andanother gas is used as the gas containing carbon monoxide, theconcentration of carbon monoxide contained in the mixed gas ispreferably not less than 10 vol %, more preferably not less than 25 vol%, much more preferably not less than 50 vol %, particularly preferablynot less than 75 vol %.

The gas containing carbon monoxide preferably contains substantially nooxygen. More specifically, the concentration of oxygen in the gas ispreferably not more than 500 ppm, more preferably not more than 100 ppm,much more preferably not more than 50 ppm, particularly preferably notmore than 10 ppm

The cobalt carbonyl complex composition of the present inventionpreferably contains substantially no oxygen dissolved therein. Morespecifically, the concentration of oxygen dissolved in the compositionis preferably not more than 500 ppm, more preferably not more than 100ppm, much more preferably not more than 50 ppm, particularly preferablynot more than 10 ppm. To reduce the concentration of oxygen dissolved inthe composition, a method using a solvent which has been bubbled with agas containing substantially no oxygen and a method using a solventwhich has been deaerated by heating is used. In the case of the formermethod, it is preferred to use a gas containing carbon monoxide as thegas used for bubbling because the number of steps for producing thecobalt carbonyl complex composition of the present invention can bereduced.

[Method of Forming a Cobalt Film]

A description is subsequently given of the method of forming a cobaltfilm from the above cobalt carbonyl complex composition by chemicalvapor deposition.

The method of forming a cobalt film is characterized in that a cobaltcarbonyl complex derived from the above cobalt carbonyl complexcomposition is sublimated, supplied onto a substrate and converted intocobalt on the substrate. Thereby, the cobalt carbonyl complex containedin the cobalt carbonyl complex composition can be sublimated at a highefficiency and converted into cobalt.

To sublimate the cobalt carbonyl complex derived from the cobaltcarbonyl complex composition, after the solvent is removed from thecomposition, the cobalt carbonyl complex may be sublimated from theresidue, or the cobalt carbonyl complex may be sublimated simultaneouslywith the evaporation of the solvent from the composition.

In the case of the former method, the removal of the solvent from thecobalt carbonyl complex composition can be carried out by a method inwhich an inert gas, a reducing gas or a mixture thereof is let passthrough the composition, a method in which the composition is heated, ora method in which the composition is put under a reduced pressure. Outof these, the method in which an inert gas, a reducing gas or a mixturethereof is let pass through the cobalt carbonyl complex composition ispreferred. Examples of the inert gas and the reducing gas used in themethod are the same as those enumerated above. The temperature of thecomposition at the time of aeration is preferably kept at 10 to 50° C.The sublimation of the cobalt carbonyl complex which is carried outsubsequently can be carried out by heating the residue after the removalof the solvent at preferably 25° C. or higher, more preferably 40 to500° C., much more preferably 40 to 300° C.

Meanwhile, in the case of the latter method in which the cobalt carbonylcomplex is sublimated simultaneously with the evaporation of the solventfrom the cobalt carbonyl complex composition, the composition is kept atpreferably 25 to 100° C., more preferably 30 to 100° C., much morepreferably 35 to 50° C. for preferably 0.1 to 60 minutes, morepreferably 1 to 20 minutes. The atmosphere for the removal of thesolvent is preferably an atmosphere of an inert gas such as nitrogen,argon or helium, a reducing gas such as hydrogen or carbon monoxide, ora mixture thereof.

It is particularly preferred that the cobalt carbonyl complex should besublimated from the residue after the solvent is removed from the cobaltcarbonyl complex composition. In this case, the solvent removed from thecobalt carbonyl complex composition is preferably discharged to theoutside of the system.

To supply a sublimate of the above cobalt carbonyl complex onto thesubstrate, a method in which the sublimation of the above cobaltcarbonyl complex is carried out in the vicinity of the substrate or amethod in which the sublimation of the cobalt carbonyl complex iscarried out away from the substrate or in another reactor (chamber) andthe produced sublimate is carried to a position near the substrate byusing a suitable carrier gas or a pressure difference may be employed.

In the method in which the sublimation of the above cobalt carbonylcomplex is carried out in the vicinity of the substrate, for example,the cobalt carbonyl complex is sublimated while the cobalt carbonylcomplex composition contained in a suitable container is placed near thesubstrate, or the cobalt carbonyl complex is sublimated while thesurface on which a cobalt film is to be formed of the substrate and thecomposition placed surface of another substrate are opposed to eachother after the composition is placed on the surface of the othersubstrate different from the substrate on which the cobalt film is to beformed. At this point, the solvent is preferably removed from the cobaltcarbonyl complex composition placed on the other substrate in advance.

Out of these, the latter method using the other substrate is preferred.The other substrate is not particularly limited as long as a coatingfilm of the above cobalt carbonyl complex composition can be formed bycoating and the substrate can withstand heat for the sublimation of thecobalt carbonyl complex. A substrate made of the same material as thatof the substrate on which the cobalt film is to be formed may be used.The shape of the other substrate is not particularly limited but a shapehaving a surface to be mated with at least part of a portion (surface)on which the cobalt film is to be formed of the substrate is preferred.The cobalt carbonyl complex composition may be placed on the surface ofthe other substrate, for example, by coating the surface of the othersubstrate with the above cobalt carbonyl complex composition.

Meanwhile, when the sublimation of the cobalt carbonyl complex iscarried out away from the substrate or in the other reactor (chamber)and the produced sublimate is carried to a position near the substrateby a suitable carrier gas, the used carrier gas is an inert gas, areducing gas or a mixture thereof. Examples of the gas are the same asthose enumerated above. When the sublimation of the cobalt carbonylcomplex is carried out away from the substrate or in the other reactor(chamber) and the produced sublimate is carried to a position near thesubstrate by a pressure difference, the inside pressure of the reactoris reduced by using a vacuum pump to carry the cobalt carbonyl complexinto the reactor.

The cobalt carbonyl complex supplied onto the substrate is convertedinto cobalt on the substrate, thereby forming a cobalt film on thesubstrate. The conversion of the cobalt carbonyl complex into cobalt onthe substrate may be carried out by heating the surface of thesubstrate.

The temperature of the surface of the substrate for converting thecobalt carbonyl complex into cobalt is preferably 50 to 300° C., morepreferably 50 to 250° C., much more preferably 50 to 150° C.

<Substrate>

Examples of the material of the substrate on which the cobalt film is tobe formed by chemical vapor deposition using the container containing acobalt carbonyl complex or the cobalt carbonyl complex compositioninclude glasses, metals, metal nitrides, silicon, resins and insulatingfilms. The above glasses include quartz glass, borate glass, soda glassand lead glass. The above metals include gold, silver, copper, nickel,aluminum and iron. The above metal nitrides include titanium nitride,tantalum nitride and tungsten nitride. The above resins includepolyethylene terephthalate, polyimide and polyether sulfone. The aboveinsulating films include silicon oxide, titanium oxide, zirconium oxide,hafnium oxide, tantalum oxide and niobium oxide, insulating film called“SOG”, and insulating film having a low dielectric constant formed byCVD. Examples of the above silicon oxide include a thermally oxide film,PETEOS (Plasma Enhanced TEOS) film, HDP (High Density Plasma EnhancedTEOS) film, BPSG (Boron Phosphorus Silicate Glass) film and FSG(Fluorine Doped Silicate Glass) film.

The above thermally oxide film is formed by placing silicon in ahigh-temperature oxidizing atmosphere. The PETEOS film is formed fromtetraethyl orthosilicate (TEOS) by chemical vapor deposition making useof plasma as an acceleration condition. The HDP film is formed fromtetraethyl orthosilicate (TEOS) by chemical vapor deposition making useof high-density plasma as an acceleration condition. The BPSG film canbe obtained, for example, by normal-pressure or vacuum CVD. The FSG filmis formed by chemical vapor deposition making use of high-density plasmaas an acceleration condition.

The above SOG stands for Spin On Glass and refers to an insulating filmhaving a low dielectric constant obtained by spin coating a liquidmixture prepared by dissolving or dispersing a silicate compound as aprecursor in an organic solvent to a substrate and heating it. Thesilicate compound as a precursor is, for example, silsesquioxane.Commercially available products of the insulating film called “SOG”include Coral (of Nuvellus System Inc.), Aurola (of ASM Japan K.K.),Nonaglass (of Honeywell International Inc.) and LKD (of JSRCorporation). The material forming the substrate is preferably a siliconoxide film, insulating film called “SOG” or insulating film having a lowdielectric constant formed by CVD, more preferably a silicon oxide film,much more preferably a PETEOS film, BPSG film or FSG film.

The substrate may have a barrier layer formed on the surface. Examplesof the material of the barrier layer include tantalum, titanium,tantalum nitride and titanium nitride, out of which tantalum andtantalum nitride are preferred.

The substrate on which a cobalt film is to be formed produces theadvantageous effect of the present invention when it has trenches. Thetrenches are formed in the substrate made of the above material by aknown method such as photolithography.

Although the trenches may be of any shape or any size, when the openingwidth (the minimum distance of a portion open to the surface of thesubstrate) of each trench is 10 to 300 nm and the aspect ratio (a valueobtained by dividing the depth of the trench to the opening width of thetrench) of the trench is 3 or more, the advantageous effect of thepresent invention is produced to a maximum extent. The opening width ofthe trench may be 10 to 200 nm, specifically 10 to 100 nm, morespecifically 10 to 50 nm. The aspect ratio of the trench may be 3 to 40,specifically 5 to 25.

<Cobalt Film>

The thickness of the cobalt film formed by using the containercontaining a cobalt carbonyl complex of the present invention or thecobalt carbonyl complex composition of the present invention ispreferably 1 to 1,000 nm, more preferably 10 to 500 nm.

The method of forming the above cobalt film can be advantageouslyapplied to a seed layer for burying copper in trenches by plating and abarrier layer at the interface between an insulator and copper becausethe cobalt precursor can be sublimated at a high efficiency andconverted into cobalt and the cobalt film formed on the substrate ishomogeneous with a uniform thickness and high quality as obvious fromexamples which will be given hereinafter.

Examples Manufacture of Container Containing a Cobalt Carbonyl Complexand Storage Stability Test Example A-1 Manufacture of ContainerContaining a Cobalt Carbonyl Complex

Octacarbonyl dicobalt was prepared as the cobalt carbonyl complex. 10 gof the above octacarbonyl dicobalt was contained in a SUS304 containerhaving a capacity of 100 ml in a carbon monoxide atmosphere (1 atm,oxygen concentration of 1 ppm), and the container was closed up with alid to manufacture a container containing a cobalt carbonyl complex.

[Evaluation of Storage Stability]

The container containing a cobalt carbonyl complex manufactured abovewas left and kept in a 40° C. oven (filled with air) for 1 month.

After 1 month of storage, the content was taken out from the containercontaining a cobalt carbonyl complex in a nitrogen atmosphere. Thecontent was dissolved in a mixed solvent of deuterated toluene andhexane in a weight ratio of 1:1 to a concentration of 5 wt %. ⁵⁹Co-NMRmeasurement was made on this solution to check the conversion of thecobalt carbonyl complex into dodecacarbonyl tetracobalt as a stablecomplex. The change rate as the proportion of the weight ofdodecacarbonyl tetracobalt to the weight of the whole cobalt carbonylcomplex after storage was 0%.

Comparative Example A-1

A container containing a cobalt carbonyl complex was manufactured in thesame manner as in Example A-1 except that the atmosphere for containingoctacarbonyl dicobalt in the container was changed to a nitrogenatmosphere (1 atm, oxygen concentration of 1 ppm) to evaluate itsstorage stability. The change rate after 1 month of storage at 40° C.was 6%.

Example A-2

A container containing a cobalt carbonyl complex was manufactured in thesame manner as in Example A-1. The container containing a cobaltcarbonyl complex was left and kept in a 70° C. oven (filled with air)for 12 hours.

When the change rate after storage was measured in the same manner as inExample A-1 after 12 hours, it was 55%.

Comparative Example A-2

A container containing a cobalt carbonyl complex was manufactured in thesame manner as in Example A-2 except that the atmosphere for containingoctacarbonyl dicobalt in the container was changed to a nitrogenatmosphere (1 atm, oxygen concentration of 1 ppm) to evaluate itsstorage stability. The change rate after 12 hours of storage at 70° C.was 80%.

Cobalt Film Formation Test Example A-3 Manufacture of ContainerContaining a Cobalt Carbonyl Complex

Octacarbonyl dicobalt was prepared as the cobalt carbonyl complex.

A SUS304 container having a container body with a capacity of 100 ml anda gas introduction port and a gas exhaust port formed in the containerbody was prepared as the container.

500 mg of octacarbonyl dicobalt was contained in the above container ina carbon monoxide atmosphere (1 atm, oxygen concentration of 1 ppm), andthe gas introduction port and the gas exhaust port were closed up tomanufacture a container containing a cobalt carbonyl complex.

[Storage]

The container containing a cobalt carbonyl complex manufactured abovewas left and kept in an 40° C. oven (filled with air) for 1 month.

[Formation of Cobalt Film]

After one month, the gas introduction port of the container containing acobalt carbonyl complex after storage was connected to a nitrogen supplysource and the gas exhaust port was connected to a reactor in which asubstrate (silicon wafer having a diameter of 100 mm) was set.

Then, the substrate was heated on a hot place installed at the back toraise the temperature of the surface of the substrate to 120° C.Subsequently, the container containing a cobalt carbonyl complex washeated with an oil bath to raise the temperature of octacarbonyldicobalt to 40° C. so as to sublimate it while nitrogen was let flowfrom the gas introduction port as a carrier gas at a rate of 1 liter(SATP)/min, and the sublimate was supplied onto the substrate placed ina reactor through the gas exhaust port by the above carrier gas. As aresult, a silver white film having a thickness of 160 nm was formed onthe substrate. When SIMS analysis (secondary ion mass spectrometry) wasmade on this film, it was found that this film was made of cobalt metal.The resistivity of this cobalt film was 18 μΩcm.

After the formation of the cobalt film, the weight of the cobaltcarbonyl complex remaining in the container was 0 mg, and the residualratio was 0%.

Comparative Example A-3

When a container containing a cobalt carbonyl complex was manufacturedin the same manner as in Example A-3 except that the atmosphere forcontaining octacarbonyl dicobalt in the container was changed to anitrogen atmosphere (1 atm, oxygen concentration of 1 ppm) and then acobalt film was formed after this container was left and kept at 40° C.for 1 month, a silver white film having a thickness of 150 nm was formedon the substrate. When SIMS analysis was made on this film, it was foundthat this film was made of cobalt metal. The resistivity of this cobaltfilm was 18 μΩcm.

After the formation of the cobalt film, the weight of the cobaltcarbonyl complex remaining in the container was 2 mg, and the residualratio was 6.7 t.

Stability Test of Cobalt Carbonyl Complex Composition Example B-1 (1)Preparation of Cobalt Carbonyl Complex Composition

20 g of octacarbonyl dicobalt was dissolved in 180 g of hexane intowhich carbon monoxide had been bubbled at a flow rate of 1 liter(NTP)/min at 25° C. for 2 minutes to prepare a cobalt carbonyl complexcomposition having an octacarbonyl dicobalt concentration of 10 wt %.All these operations were conducted in a carbon monoxide atmosphere.When the concentration of carbon monoxide dissolved in the above hexaneused as a solvent was measured by gas chromatography (6890N of AgilentTechnologies Inc.), it was 0.12 wt %. The concentration of oxygencontained in hexane was 1 ppm.

(2) Storage of Cobalt Carbonyl Complex Composition

200 g of the above cobalt carbonyl complex composition was put into a500 ml container in a carbon monoxide atmosphere, and the container wasclosed up with a lid. This container was left and kept in a 40° C. ovenfor 1 month.

(3) Analysis of Cobalt Carbonyl Complex Composition after Storage

Part of the content was taken out from the above container in a nitrogenatmosphere and dissolved in a mixed solvent of deuterated toluene andn-hexane in a weight ratio of 1:1 to prepare a solution having aconcentration of 5 wt %. ⁵⁹Co-NMR measurement was made on this solutionto check the ratio of octacarbonyl dicobalt and dodecacarbonyltetracobalt. Dodecacarbonyl tetracobalt was not found in the compositionafter storage, and the change rate of octacarbonyl dicobalt intododecacarbonyl tetracobalt (ratio of the weight of dodecacarbonyltetracobalt to the whole weight of the cobalt complex contained in thecomposition after storage) was 0%.

Example B-2

A cobalt carbonyl complex composition was prepared in the same manner asin Example B-1 except that the gas used for bubbling the solvent waschanged to a mixed gas having a monoxide concentration of 75 vol % and anitrogen concentration of 25 vol % and that all the operations wereconducted in an atmosphere of a mixed gas having a monoxideconcentration of 75 vol % and a nitrogen concentration of 25 vol % in“(1) preparation of cobalt carbonyl complex composition” of Example B-1.The solvent had a carbon monoxide content of 0.09 wt % and an oxygencontent of 1 ppm.

When the above composition was kept for 1 month in the same manner as inExample B-1 and analyzed, the change rate of octacarbonyl dicobalt intododecacarbonyl tetracobalt after storage was 0%.

Example B-3

A cobalt carbonyl complex composition was prepared in the same manner asin Example B-1 except that the gas used for bubbling the solvent waschanged to a mixed gas having a monoxide concentration of 50 vol % and anitrogen concentration of 50 vol % and that all the operations wereconducted in an atmosphere of a mixed gas having a monoxideconcentration of 50 vol % and a nitrogen concentration of 50 vol % in“(1) preparation of cobalt carbonyl complex composition” of Example B-1.The solvent had a carbon monoxide content of 0.06 wt % and an oxygencontent of 1 ppm.

When the above composition was kept for 1 month in the same manner as inExample B-1 and analyzed, the change rate of octacarbonyl dicobalt intododecacarbonyl tetracobalt after storage was 1%.

Comparative Example B-1

A cobalt carbonyl complex composition was prepared in the same manner asin Example B-1 except that the gas used for bubbling the solvent waschanged to a nitrogen and that all the operations were conducted in anitrogen atmosphere in “(1) preparation of cobalt carbonyl complexcomposition” of Example B-1. The solvent had a carbon monoxide contentof 0.00 wt % and an oxygen content of 1 ppm.

When the above composition was kept for 1 month in the same manner as inExample B-1 and analyzed, the change rate of octacarbonyl dicobalt intododecacarbonyl tetracobalt after storage was 10%.

Cobalt Film Formation Test Example B-4

A silicon wafer (first substrate) having a tantalum nitride film with athickness of 50 nm as a substrate on which a cobalt film was to beformed and a silicon wafer (second substrate) as another substrate wereprepared.

(1) Formation of Cobalt Carbonyl Complex Film on Second Substrate

The cobalt carbonyl complex composition which had been left and kept for1 month in the above Example B-1 as the cobalt carbonyl complexcomposition was applied to one side of the second substrate in anitrogen atmosphere by spin coating to form a uniform film of the cobaltcarbonyl complex having a thickness of about 3 μm on the secondsubstrate. The weight of this film was 30 mg.

(2) Formation and Evaluation of Cobalt Film on First Substrate

The surface having a tantalum nitride film of the above first substrateand the surface having the cobalt carbonyl complex film of the secondsubstrate were opposed to each other with a distance of 2.0 mmtherebetween in a nitrogen atmosphere. At this point, the firstsubstrate was arranged above the second substrate. The back surface ofthe first substrate was brought into contact with the surface of a hotplate to heat the substrate at 120° C. for 10 minutes. The cobaltcarbonyl complex on the second substrate was sublimated by heating withradiation heat from the heated first substrate, and a silver white filmhaving a thickness of 200 nm was formed on the first substrate. WhenSIMS analysis was made on this film, it was found that the film was madeof cobalt metal. The resistivity of this cobalt film was 18 μΩ·cm.

After the formation of the cobalt film, the weight of the cobaltcarbonyl complex remaining on the second substrate was 0 mg, and theresidual ratio was 0%.

Example B-5

A cobalt film was formed on the first substrate in the same manner as inExample B-4 except that the cobalt carbonyl complex composition whichhad been left and kept for 1 month in the above Example B-2 was used asthe cobalt carbonyl complex composition.

As a result, the obtained cobalt film had a thickness of 200 nm and aresistivity of 18 μΩ·cm. After the formation of the cobalt film, theweight of the cobalt carbonyl complex remaining on the second substratewas 0 mg, and the residual ratio was 0%.

Example B-6

A cobalt film was formed on the first substrate in the same manner as inExample B-4 except that the cobalt carbonyl complex composition whichhad been left and kept for 1 month in the above Example B-3 was used asthe cobalt carbonyl complex composition.

As a result, the obtained cobalt film had a thickness of 200 nm and aresistivity of 18 μΩ·cm.

After the formation of the cobalt film, the weight of the cobaltcarbonyl complex remaining on the second substrate was 0 mg, and theresidual ratio was 0%.

Comparative Example B-2

A cobalt film was formed on the first substrate in the same manner as inExample B-4 except that the cobalt carbonyl complex composition whichhad been left and kept for 1 month in the above Comparative Example B-1was used as the cobalt carbonyl complex composition.

As a result, the obtained cobalt film had a thickness of 190 nm and aresistivity of 20 μΩ·cm. After the formation of the cobalt film, theweight of the cobalt carbonyl complex remaining on the second substratewas 4 mg, and the residual ratio was 13%.

EFFECT OF THE INVENTION

The container containing a cobalt carbonyl complex of the presentinvention can store a cobalt carbonyl complex contained therein stably.The cobalt carbonyl complex composition of the present invention canstore a cobalt carbonyl complex contained therein stably. The cobaltcarbonyl complex contained in the container and the composition canretain its sublimation properties for a long time without beingconverted into a stable complex. Therefore, when a cobalt film is formedby using the container containing a cobalt carbonyl complex of thepresent invention or the cobalt carbonyl complex composition of thepresent invention, a high-quality cobalt film can be formed by a simpleprocess, and the production cost of the cobalt film can be reduced dueto high use efficiency of the precursor.

The cobalt film formed by the above method is homogeneous with a uniformthickness and high quality and can be advantageously used as a seedlayer for burying copper into trenches by plating and as a barrier layerat the interface between an insulator and copper.

1. A container containing a cobalt carbonyl complex and a gas, whereinthe gas contains carbon monoxide.
 2. The container containing a cobaltcarbonyl complex according to claim 1, wherein the concentration ofcarbon monoxide in the gas contained in the container is not less than10 vol %.
 3. The container containing a cobalt carbonyl complexaccording to claim 1, wherein the cobalt carbonyl complex is representedby any one of the following formulas (1) to (4):CO₂(CO)₈  (1)CO₃(CO)₉CZ  (2) (Z is a hydrogen atom, halogen atom, methyl group,methoxy group or trifluoromethyl group.)CO₃(CO)₁₂  (3)CO₄(CO)₁₂  (4).
 4. The container containing a cobalt carbonyl complexaccording to claim 1, wherein the cobalt carbonyl complex is provided tosublimate to form a cobalt film on a substrate, and the container isused to carry out the sublimation of the cobalt carbonyl complextherefrom.
 5. The container containing a cobalt carbonyl complexaccording to claim 4, wherein the container has a container body and agas introduction port and a gas exhaust port formed in the containerbody.
 6. The container containing a cobalt carbonyl complex according toclaim 4, wherein the container has at least partitions of a fillertherein. 7-14. (canceled)